Jfitz Posted January 11, 2023 Report Share Posted January 11, 2023 (edited) As part of a recent home build, we went with the builder's suggestion to use a 'hybrid' water heater. It has a heat pump as well as electric elements. It can run in all-heatpump ("efficiency"), a combination of heat pump and one electric element ("hybrid"), or all-electric using 2 heating elements ("electric"). I have to say I an unimpressed with the performance of the heat pump, and run the system in 'electric' as much as I can. I noticed when it is in 'hybrid' setting, the heat pump seems to run non-stop. As in, all the time. I have a recirc pump to ensure hot water is available at all times through the house, so I thought maybe that was causing too much heat loss (note - if it can't keep up with just that heat loss, it's not really a water heater IMO). So, I disabled the circ pump for a few days - and the results were the same. Once it has to run, like after washing dishes or a shower, it seemed to me that the heat pump just ran non-stop and could not catch up. Does anyone have experience with these "hybrid" water heaters? I'm close to pulling it out for a natural gas fired unit, either a tank or one of the on-demand systems. My builder wants to get a manufacturer rep in to look at it, as it doesn't seem to work as well as other's he's installed. Maybe there is something wrong with it. Edited January 11, 2023 by Jfitz Spelling Quote Link to comment Share on other sites More sharing options...
BonPacific Posted January 11, 2023 Report Share Posted January 11, 2023 My father got one of those a few years ago and absolutely loves it. But he also has an insulated crawl-space so minimal loss in the water lines, and the water heater is in the same room as his woodstove so it has ample ambient temperature to concentrate. Heat pumps, AFAIK, are intended to run low and often. They're not great at quick changes in temperature. Is there enough airflow around your water heater? And is it in conditioned space? If it's stuck out in a cold garage or an old water heater closet the heat pump won't be as effective. Could also just be a bum unit as your builder suspects, or wasn't sized properly for your house if it's having to play catch-up like that. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted January 11, 2023 Report Share Posted January 11, 2023 That seems to have an issue as they are supposed to be great. They heat a bit slower than using just the electrical heating elements but that's why they have the hybrid feature for those times with high water draw. I find it hard to believe that it's more efficient cost wise than a natural gas unit. Our cloths dryer, range, oven , and water heater are all natural gas and the 3 combined don't use enough gas in the summer months to have the gas company bill me for more than their "minimum bill" Is it possible that the heater is located in a space that isn't warm enough? My main drawback with the heat pump water heaters is my water heater is in the coldest part of my house. If it was then pumping heat out of the space cooling it off further I'd have to run a space heater in the summer to keep the room warm enough. The "room" is my wood shop and mid summer it peaks at 63-64 degrees. I must confess i don't understand recirc pumps but maybe it's because I've always lived in houses where the hot water run is short. It takes 5 seconds to get hot water at the furthest point in our house. Quote Link to comment Share on other sites More sharing options...
BonPacific Posted January 11, 2023 Report Share Posted January 11, 2023 On 1/11/2023 at 9:57 AM, Chestnut said: I must confess i don't understand recirc pumps but maybe it's because I've always lived in houses where the hot water run is short. It takes 5 seconds to get hot water at the furthest point in our house. In my experience it's usually oversized pipes for low-flow fixtures rather than long runs. Definitely lived in houses where it took several minutes to get warm water, and even longer for proper hot. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted January 11, 2023 Author Report Share Posted January 11, 2023 On 1/11/2023 at 12:25 PM, BonPacific said: Is there enough airflow around your water heater? And is it in conditioned space? Great question. The 'room' it is in is small (maybe 5'x8', 8'+ ceiling) but during all this I was leaving the door open into my soon-to-be-shop (maybe 220sf, unheated but in a basement that was maintaining 60degF or warmer). Definitely made the 'small' room colder, but they're supposed to run down to 40 degF or so. On 1/11/2023 at 12:57 PM, Chestnut said: I must confess i don't understand recirc pumps This was a 'nice to have' thing. The run from the basement to the second floor bathrooms is a little long, and I hate waiting for hot water. On 1/11/2023 at 12:25 PM, BonPacific said: or wasn't sized properly for your house This is also possible - when the kids are home, it's 5 of us. We were seeing issues when it was just and our daughter though, and the unit is supposed to be for 'up to 4 people). It's a 50 gallon tank, which is about the same as the previous house. Quote Link to comment Share on other sites More sharing options...
BonPacific Posted January 11, 2023 Report Share Posted January 11, 2023 Sounds like it's probably a combination of issues. They'll work in low temps, but their efficiency goes down (which is where the electric should be kicking in), and I imagine that "up to 4" is for much warmer climes than Massachusetts and probably with the water thermostat turned lower. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted January 12, 2023 Report Share Posted January 12, 2023 @Jfitz, I can guarantee you won't be disappointed in the performance of a gas-fired tank unit. Several 'on-demand' unit owners I know have not been impressed. Quote Link to comment Share on other sites More sharing options...
JohnG Posted January 12, 2023 Report Share Posted January 12, 2023 I’d let the rep come look at it, but I’ve heard mixed reviews on them from people I know. A couple love it and one hates it. I have a different type of hybrid water heater that I love, but that experience doesn’t apply here. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted March 16, 2023 Author Report Share Posted March 16, 2023 Following up on this thread ... we're having the plumber in (today, actually) to replace it with a gas fired unit. With some of the long runs and the recirc pump, the hybrid just clearly could not keep up when in hybrid mode. I've had it in full electric mode for the most part, but power is so expensive here it's not worth it. The rep never actually came out - apparently they rarely due since COVID - but he had some interesting info for the plumber which just reinforces it is not right for us. 1 Quote Link to comment Share on other sites More sharing options...
pkinneb Posted March 16, 2023 Report Share Posted March 16, 2023 On 3/16/2023 at 10:59 AM, Jfitz said: Following up on this thread ... we're having the plumber in (today, actually) to replace it with a gas fired unit. With some of the long runs and the recirc pump, the hybrid just clearly could not keep up when in hybrid mode. I've had it in full electric mode for the most part, but power is so expensive here it's not worth it. The rep never actually came out - apparently they rarely due since COVID - but he had some interesting info for the plumber which just reinforces it is not right for us. Thanks for reporting back!! Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 17, 2023 Report Share Posted March 17, 2023 Well gas fired units are hard to beat imo. Gas is effective and inexpensive so far. I've been thinking about getting an on demand unit when our current one gets old. Quote Link to comment Share on other sites More sharing options...
Mark J Posted March 17, 2023 Report Share Posted March 17, 2023 I'm curious about on demand water heaters, too. I remember these were being talked about a lot 30 years ago, but they don't seem to have caught on, at least not around here. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 17, 2023 Report Share Posted March 17, 2023 This old house discusses them a lot. I think it has to do with the fact that venting needs to be through PVC pipe instead of out the already existing chimny. Also electric on demand heaters don't really work well. Quote Link to comment Share on other sites More sharing options...
legenddc Posted March 17, 2023 Report Share Posted March 17, 2023 I'll speak with my neighbor who has an on-demand one and see if his is electric or gas. The vacation house we've stayed at the last couple of years has an on-demand one. It works well but seems underpowered for the 5 bathrooms at the house. You don't want to have 3 showers running at the same time. I've seen on This Old House you can run multiple units in a series to avoid that. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted March 17, 2023 Author Report Share Posted March 17, 2023 On 3/17/2023 at 10:50 AM, legenddc said: It works well but seems underpowered for the 5 bathrooms I think this has been of of the "big issues" with these units over the years. From what I've heard they are now much better about handling varying demands. you definitely want to right-size it. When I discussed it with our plumber, he sized it to handle all of the loads in the house (3.5 bathrooms, 2 dishwashers, laundry, and a tub). We haven't run anything all at once yet, but hopefully we don't run into issues. I made a comment to the plumber about having the HW run constantly, and he shared a story about a friend of his that put a slip and slide in the backyard for the kids or a party or something. He turned the unit down to 90degF, and used that for the s&s, and it just ran for hours and hours with no issues. I'll still turn the HW off if one of the kids takes a marathon shower , but it's good to know the supply will always be there. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 17, 2023 Report Share Posted March 17, 2023 22 minutes ago, legenddc said: You don't want to have 3 showers running at the same time. Man in my childhood house you could only run 1 shower at a time even with a tank heater. The hot water was gone instantly with 2 showers running. 16 minutes ago, Jfitz said: When I discussed it with our plumber, he sized it to handle all of the loads in the house (3.5 bathrooms, 2 dishwashers, laundry, and a tub). We haven't run anything all at once yet, but hopefully we don't run into issues. Did you get an on demand unit then? Also 2 dishwashers; a house with 5 showers ... i feel like I live a considerably different life that is a lot more austere. I don't even know if the water line to our house would support 3 showers running at the same time. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted March 17, 2023 Author Report Share Posted March 17, 2023 On 3/17/2023 at 11:20 AM, Chestnut said: in my childhood house you could only run 1 shower at a time even Same. Of course, growing up it's 'cause we only had the one shower. with 9 kids On 3/17/2023 at 11:20 AM, Chestnut said: Did you get an on demand unit then? We did. I thought about a more conventional tank system but got enough good feedback from people I know, who like their demand system. On 3/17/2023 at 11:20 AM, Chestnut said: I don't even know if the water line to our house would support 3 showers running at the same time Haha - that's a good point. We just built our 'forever home' and while it's just the two of us most of the time, the kids are home a lot, and I expect at some point grandkids as well, so we went a little overboard in some regards. 1 Quote Link to comment Share on other sites More sharing options...
legenddc Posted March 17, 2023 Report Share Posted March 17, 2023 On 3/17/2023 at 11:20 AM, Chestnut said: Also 2 dishwashers; a house with 5 showers ... i feel like I live a considerably different life that is a lot more austere. I don't even know if the water line to our house would support 3 showers running at the same time. Vacation house with 15+ of our family. We only have 2.5 bathrooms at home. Wouldn't mind 2 dishwashers though. Just pull the clean stuff out of the one and load it into the other when it was dirty. Would save some cabinet space. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted March 17, 2023 Report Share Posted March 17, 2023 1 hour ago, legenddc said: Wouldn't mind 2 dishwashers though. Just pull the clean stuff out of the one and load it into the other when it was dirty. Would save some cabinet space. Ok i can get on board with that idea. Quote Link to comment Share on other sites More sharing options...
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